A. Field of the Invention
The present invention relates generally to apparatus and methods for treating and conditioning liquids, in particular water.
B. Description of the Related Art
The need to preserve adequate supplies of pure, potable water has engendered a number of approaches to water purification. These approaches reflect the increasing environmental stress imposed by modern industrial society, and the difficulty of isolating water sources and reservoirs from the effects of such stress. For example, acid rain produced by smokestack discharge can adversely affect the chemical composition of waters far removed from the site of the actual discharge by altering pH levels and causing dissolution of heavy metals that would otherwise lie dormant.
Current treatment methods frequently involve addition of chemicals such as chlorine gas, bleach, sodium hydroxide, ozone, sodium fluoride or sodium hexametaphosphate. Unfortunately, the net result is often replacement of one set of chemical contaminants with another, less offensive set that the public consumes through drinking and cooking Furthermore, the efficacy of treatment chemicals is usually limited both by their intrinsic properties and safe concentration levels.
The need for fluid conditioning can arise from concerns other than water potability. For example, many industries employ large quantities of treatment chemicals in an effort to reduce corrosion and fouling of equipment such as boilers, cooling towers, refrigerators and compressors; similar treatment of fuel compositions can enhance combustion efficiency. The chemicals employed in these processes and their byproducts are ultimately introduced into the environment as effluent or exhaust.
As an alternative to chemical treatment, practitioners in the art have developed certain metal alloys which, when brought into contact with an impure fluid, produce various beneficial effects; see, e.g., U.S. Pat. Nos. 4,429,665 and 4,959,155. The mechanism by which these alloys produce such effects is not clearly understood, rendering their identification largely a matter of experimental effort. Also for this reason, the effect of substituting alloy components or adjusting their ranges cannot readily be predicted from traditional metallurgy concepts, nor can it be assumed that different alloys will provide similar types of conditioning effects.
Alloy-based fluid-conditioning systems can operate catalytically or sacrificially; in the latter case, the alloy core gradually disintegrates into the water to be treated. Although catalytic systems are obviously preferable, it is not generally possible to tell, merely from structural and metallurgical description of an apparatus, whether it retains integrity during operation.